With the advance of semiconductor packaging technology, it has been possible to mount a plurality of integrated circuit chips in a package. By this, a rapid progress has been made in high functionality and high integration of a semiconductor device.
In such a semiconductor device, a protruding electrode (bump), formed of a low melting point metal, bonds semiconductor integrated circuits, or a semiconductor integrated circuit and a package substrate. (For example, refer to Japanese Laid-Open Patent Publication NO. 11-54565)